Auxiliary power steering for motor vehicles

Abstract

A power steering gear assembly having a single control valve suitable for use in a single circuit type of power steering system, may be simply converted to use in a two-circuit type of power steering system by replacement of the steering spindle and the addition of a housing extension enclosing a second control valve formed on the replaced steering spindle. Both control valves include portions of the common steering spindle and control sleeves rotatable thereon, with one of the control sleeves being formed in one piece with the worm shaft of the steering gear assembly.

What is claimed is: 
     
       1. For use in a dual power steering system having two separate servomotors (13 and 16) respectively supplied with pressurized fluid from separate pumps (21 and 26) through separate control circuits to jointly perform vehicle steering operations in response to rotation of a common steering spindle (1) rotatably mounted within and axially projecting from a steering gear housing (8) associated with one of the servomotors (13), a steering control valve assembly comprising, first rotatable valve means (4-6) mounted within the housing on said common steering spindle for controlling said supply of fluid from one of the pumps (21), and second rotatable valve means (5-7) mounted on said common steering spindle in axially spaced relation to said first valve means for controlling said supply of fluid from the other of the pumps (26), said first and second rotatable valve means including control sleeves (6, 7) rotatable on the spindle, and axial passages (31, 40) formed in the spindle in operative relation to the control sleeves, and a tubular drive shaft (3) driven by said one of the servomotors (13) and coupled to said control sleeves in coaxial relation to the common steering spindle. 
     
     
       2. The combination as defined in claim 1, wherein said one of the servomotors includes a piston (13) reciprocably mounted within the steering gear housing, and means (23) drivingly connecting the tubular shaft to the piston for rotation thereof in response to reciprocation of the piston, control sleeve (6) of said first valve means being formed in one piece with said tubular shaft. 
     
     
       3. For use in a dual power steering system having two separate servomotors (13 and 16) respectively supplied with pressurized fluid from separate pumps (21 and 26) through separate control circuits to jointly perform vehicle steering operations in response to rotation of a common steering spindle (1) rotatably mounted within and axially projecting from a steering gear housing (8) associated with one of the servomotors (13), a steering control valve assembly comprising, first rotatable valve means (4-6) mounted within the housing on said common steering spindle for controlling said supply of fluid from one of the pumps (21), second rotatable valve means (5-7) mounted on said common steering spindle externally of the housing in axially spaced relation to said first valve means and operatively coupled thereto for controlling said supply of fluid from the other of the pumps (26), and auxiliary housing means (80) for enclosing the second valve means in coaxial relation to the common steering spindle, said one of the servomotors including a piston (13) reciprocably mounted within the steering gear housing, a tubular shaft (3) torsionally coupled to the steering spindle within the housing and means (23) drivingly connecting the tubular shaft to the piston for rotation thereof in response to reciprocation of the piston, said first valve means including a control valve sleeve (6) formed in one piece with said tubular shaft, said first and second valve means further including axial passage grooves (31,40) formed in the common steering spindle. 
     
     
       4. The steering control valve assembly as defined in claim 3, wherein said auxiliary housing means comprises a tubular housing extension having a flanged portion secured to the steering gear housing. 
     
     
       5. The steering control valve assembly as defined in claim 3, wherein said second valve means includes a control valve sleeve (7) coaxially mounted on the common steering spindle and rotationally coupled to the tubular shaft. 
     
     
       6. A steering gear assembly for a dual power steering system, including a housing (8), a steering spindle (1) rotatably mounted within the housing and projecting axially therefrom, a tubular drive shaft (3) rotatably mounted in coaxial relation to the steering spindle and torsionally coupled thereto within the housing, a first control valve (4-6) mounted on the steering spindle within the housing, and a second control valve (5-7) mounted on the steering spindle in axially spaced relation to the first control valve, each of said control valves including a control sleeve (6, 7) rotatably mounted on the steering spindle and an axial passage groove (31,40) formed in the steering spindle in operative relation to the associated control sleeve, one of said control sleeves (6) being formed in one piece with the tubular drive shaft and means (11) coupling the other of the control sleeves (7) to the tubular drive shaft for rotation therewith.